With the in vitro, in ovo and in vivo models for acquired immunodeficiency syndrome-Kaposi's sarcoma (AIDS-KS), developed in our laboratory, we have been able to demonstrate that: 1) the growth of AIDS-KS-derived cells is enhanced by corticosteroids; 2) AIDS-KS cells secrete factors, which not only induce angiogenesis, but also increase vascular permeability; 3) AIDS-KS cells produce interleukin (IL)-6 and IL-8; 4) AIDS-KS cells have high affinity receptors for IL-1, IL-2, IL-6, platelet-derived growth factor, basic fibroblast growth factor, tumor necrosis factor et, hydrocortisone and the human immunodeficiency virus type 1 Tat protein. We have purified and begun the sequencing of the activated T-cell-derived 30 kilodalton protein, which is a very potent stimulator of KS cell growth. Different drugs have been tested for their effect on KS cell growth in vitro and induction of KS-like lesions in nude mice. So far, one compound (SPPG, a bacterial cell wall peptidoglycan), has shown the highest specificity and the lowest toxicity, while inhibiting KS growth and development. This drug is therefore a potential candidate for clinical trials in the treatment of AIDS-KS. The study of T-cell colony formation in methylcellulose of peripheral blood mononuclear cells from HTLV-I-infected individuals, strongly suggests that the T-lymphocyte colony-forming cells are infected by HTLV-I and may be an important reservoir for that retrovirus. We have isolated a herpesvirus, which is similar to the recently described human herpesvirus 7. Our findings confirm the existence of a herpesvirus, distantly related to, but significantly different from human herpesvirus 6.